Unexpected? change in debug_backtrace for closures

[alexander-schranz]

Description

The following code:

$callers = \debug_backtrace();

// build cache key
$id = \sprintf('%s::%s', $callers[1]['class'], $callers[1]['function']);

var_dump($callers[1]['class']);
var_dump($callers[1]['function']);
exit;

Can also be reproduced with:

git clone git@github.com:sulu/sulu.git sulu
cd sulu
composer update --ignore-platform-reqs
php@8.4 vendor/bin/phpunit --filter="MemoizeTest::testMemoizeFirstCall"

And check: https://github.com/sulu/sulu/blob/7e9300b77f289250928ceb73e93a791d9c146bd4/src/Sulu/Component/Cache/Memoize.php#L45

Resulted in this output (PHP 8.4):

string(43) "Sulu\Component\Cache\Tests\Unit\MemoizeTest"
string(80) "{closure:Sulu\Component\Cache\Tests\Unit\MemoizeTest::testMemoizeFirstCall():53}"

But I expected this output instead (PHP 8.3):

string(43) "Sulu\Component\Cache\Tests\Unit\MemoizeTest"
string(41) "Sulu\Component\Cache\Tests\Unit\{closure}"

Is this change expected when upgrading from PHP 8.3 to 8.4? I'm fine with the change but wanted to report its an unexpected change.

PHP Version

8.4.0-dev

Operating System

macOs Montery

[bwoebi]

Yes, Closures got renamed to provide more information about their identity. That's intentional.

[bwoebi]

See: #13550.

[alexander-schranz]

@bwoebi thx for the quick response.